1. Field of the Invention
The present invention relates to optical cables and, more particularly, this invention relates to an optical cable with a plurality of ribbon stacks of optical waveguide ribbons which are arranged in at least one layer around a core element.
2. Description of the Related Art
An optical cable of this type is described in German Patent No. DE-A1-38 39 109. Its cable core consists of a plurality of chamber elements with approximately rectangular openings which are arranged around a tensile-load-resistant element. The chamber elements serve to receive ribbon stacks of optical waveguide ribbons.
Although an optical cable constructed in this manner from chamber elements provides, with appropriate wall thickness, reliable protection for the ribbon stacks against radial and circumferential forces, for the positional securing of the chamber elements, however, a special shaping of the chamber elements with sector-shaped side walls is necessary.
One aspect of the present invention is directed to a method in which, the positional securing of the ribbon stacks in optical cable can be ensured in a simpler manner.
This object is achieved in an optical cable of the type mentioned above having supporting elements designed as independent profiles which are provided in the interspaces formed by the ribbon stacks, such that the supporting elements contribute to a positional securing of the ribbon stacks.
In the optical cable of the present invention, it is therefore not necessary to provide specially shaped chamber elements. By virtue of this design, both the construction and the production of an optical cable with a plurality of ribbon stacks are simplified. According to another aspect of the invention, it is even possible to eliminate the chamber elements entirely. A design of this type is distinguished in that despite the fact that the ribbon stacks are free of chamber elements, they can be adequately secured in their position by arranging supporting elements in their interspaces.
According to another aspect of the invention, the profiles of the supporting elements extend radially somewhat further outwardly than the ribbon stacks. Thus, with this design, the supporting elements can exert a supporting pillar function with respect to radially acting transverse compressive forces.
According to another aspect of the invention, the supporting elements almost completely fill the interspaces between the ribbon stacks, that is to say without tolerance space. Thus, it is advantageously ensured that the optical waveguide ribbons collected to form ribbon stacks are held in their places in the respective ribbon stacks around the circumference. This allows positional securing of the ribbon stacks in the circumferential direction. This design is particularly useful when transverse compressive forces act in the circumferential direction. In this case it is desirable to use a flexible material for the supporting elements.
According to yet another aspect of the invention, the supporting elements only partly fill the interspaces between the ribbon stacks, that is to say there is an empty space between two adjacent ribbon stacks. They then serve primarily as radially extending spacers and supporting pillars in the interspaces of the ribbon stacks. For this function of the supporting elements, a stiff, smooth material which can be internally supported is desirable. In order to prevent this kind of supporting element from displacing or turning over, it is desirable that the supporting elements be fixed in their position.
The invention also relates to a process for producing an optical cable, wherein the supporting elements are designed as independent profiles which are introduced into the interspaces formed by the ribbon stacks in such a manner that the ribbon stacks are secured in their position.